README.md: Update according to thumbnail generation

1 files changed, 66 insertions, 0 deletions

diff --git a/thumbnail/README.md b/thumbnail/README.md
new file mode 100644
index 0000000..5bd876a
--- /dev/null
+++ b/thumbnail/README.md
@@ -0,0 +1,66 @@
+# Thumbnail generation tool for `slcl`
+
+This directory defines a separation application to be used in conjunction with
+`slcl`, aimed to update the thumbnail database automatically whenever files
+are added/removed to/from the database.
+
+### Root permissions
+
+This application requires no `root` permissions. So, in order to avoid the
+risk for security bugs, **please do not run this application as `root`**.
+
+## Requirements
+
+- A POSIX environment.
+- [`dynstr`](https://gitea.privatedns.org/xavi92/dynstr)
+(provided as a `git` submodule).
+- MagickCore
+- CMake (optional).
+
+### Ubuntu / Debian
+
+#### Mandatory packages
+
+```sh
+sudo apt install build-essential libmagickcore-6.q16-dev
+```
+
+#### Optional packages
+
+```sh
+sudo apt install cmake
+```
+
+## How to use
+### Build
+
+Similarly to `slcl`, two build environments are provided - feel free to choose
+any of them:
+
+- A mostly POSIX-compliant [`Makefile`](Makefile).
+- A [`CMakeLists.txt`](CMakeLists.txt).
+
+`thumbnail` can be built using the standard build process:
+
+#### Make
+
+```sh
+$ make
+```
+
+#### CMake
+
+```sh
+$ mkdir build/
+$ cmake ..
+$ cmake --build .
+```
+
+## Usage
+
+This tool only consumes one argument: the directory containing the instance
+database, which must be the same used by `slcl`. For example:
+
+```sh
+thumbnail ~/my-db
+```